Observations on visitors to flowering on Isla Santa Cruz, Part II. Butterflies, , ants, hover flies and stilt bugs

Item Type article

Authors McMullen, Conley K.

Download date 24/09/2021 18:57:21

Link to Item http://hdl.handle.net/1834/22320 OBSERVA TIONS' ON INSECT VISITORS TO FLOWERING PLANTS OF ISLA SANTA CRUZ. PART 11. BUITERFLIES, MOTHS, ANTS, HOVER FLIES' AND STILT BUGS by Conley K. McMullen Department 01Botany. University 01 Maryland, College Park, Maryland 20742 In Part I of this paper the author mentioned the depauperate condition of the Galapagos insect fauna which is emphasized by the presence of only one species of bee, Xylocopa darwini, the endemic carpenter bee (McMullen, 1985): This relative dearth ofinsects is also apparent in the groups discussed here. Within the archipelago only ten species of butterfly, 144 species of', seven species ofhover fly, twenty-two species of ant, and one species of stilt bug have been reported (Linsley and Usinger, 1966; Rindge, 1973; Hayes, 1975; Linsley, 19,77;Froeschner, 1985). Even fewer reports have been made as to what flowering plants are visited by these . Williams (191 I) mentioned observing the Galapagos sulfur butterfly, Phoebis sennae (recorded as Callidryas eubele) (Pieridae), at flowers of lutea (), Opuntia (Cactaceae), and Gossypium (Malvaceae) on Isla Isabela. He also reported that the hawk moth delanoi (recorded as Epistor lugubris delanol) () visited Cordia lutea at Villamil, Isabela in the bright sunlight, and Manduca rustica calapagensis (recorded as Protoparce rustica calapagensis) (Sphingidae) visited flowers of Cordia lutea and Clerodendrum molle (Verbenaceae) at Tagus Cove, IsabeIa at dusk. Beebe (1923) reported that Phoebis sennae made visits to Cordia and Gossypium on Isla San Cristóbal. He also mentioned that the moth Atteva hysginiella (Yponomeutidae) visited Cassia (Fabaceae), Cordia, and Gossypium. Wheeler (1924) reported that the an t Monomoriumj7oricola (Formicidae) visited the nectaries of Cordia lutea and Opuntia helleri on Isla Genovesa. Hayes (1975) mentioned that the carmine hawk moth, Agrius cingl/latus (Sphingidae) visited flowers of Cacabus miersii (Solanaceae), lpomoea (Convolvulaceae), and Opuntia during the day. Also mentioned were Utetheisa galapagensis (Arctiidae) which was observed flying around plants of Scalesia affinis () at dusk, Heliothis cystiphora (Noctuidae) which visited flowers of Encelia hispida (Asteraceae) during the day on Isla Santa Fe, Paectes arcigera (Noctuidae) seen near Cryptocarpus pyriformis (Nyctaginaceae), and Pseudoplusia includens (Noétuidae) which visited flowers of Clerodendrum molle and Cordia. The only mention of insect visitors to flowering plants specifically on Isla Santa Cruz, other than Xylocopa darwini, is that of Rick (1966). He reported observing flies (Diptera) visiting flowers of Borreria (Rubiaceae). The observations reported here took place on the southern slope of Santa Cruz during the months of October 1983 through March 1984. Observations of insect visitors to flowering plants were conducted in each of the seven major vegetation zone. Tables 1-41ist the flowers and visitors observed during this time, along with locations, level of activity and whether the plants are endemic or non-endemic. AII of the 22plants listed represent new insect visitation reports to flowers on Santa Cruz. Only three ofthe 22 have been reported before for the archipelago as a whole. Among the insect visitors Leptotes parrhasioides, Disc/isioprocta stellata, Wasmannia auropunctata, Tapinoma melanocephalum, Paratrechina longicornis, Paratrechina vaga, Toxomerus crockeri, Metacanthus galapagensis, and the unidentified pyralid moth are newly reported as insect visitors to flowers of the archipelago. Pollen was actually observed only on the butterfly Leptotes parrhasioides. Because of this it would be inappropriate to labeI all of these insects pollinators. However, the author does echo Linsley (1966) in suggesting that butterflies, moths, flies and ants might have possible roles in pollination beca use they play this part in continental areas. Toxomerus crockeri was very active in several flowers, as were many of the butterflies and moths. Many ant species were also very active in several flowers. This is not highly unusual because of the ant's heavy use of sugar and palien for food, and although ant morphology is not well adapted for pollen transport, the possibility does exist that with such a high level oftraffic throughout an a pollination event might occur. The same possibility applies to the stilt bug, Metacanthus galapagensis, during its feeding visits to flowers.

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Noticias de Galapagos v.43 1986 The majority of insects was observed during daylight hours. However, the moths were much more active towards dusk with the pyralid and Agrius cingulatus active at night. There appears to be no strong correlation between flower color and insect visitor other than the expected visits made by hawk moths to larger white flowers such as those of Carica papaya (Caricaceae) and Clerodendrum molle var. molle. In general, the insects visited the few different colored flowers that were available. The one obvious trend, that also shared by Xylocopa darwini, was toward non-endemic plants. Justicia galapagana (Acanthaceae), Cordia leucophlyctis (Boraginaceae), Jaegeria gracilis (Astraceae), and Gossypium barbadense var. darwinii were the only endemics observed to be visited by insects other than the carpenter bee. Therefore, these results would seem to further substantiate Linsley et al. (1966) in their observation that insect visitors may have pro ved more usefui in the establishment of the non-endemic (weedy plants and adventives) flora than for the older endemic species. ACKNOWLEDGEMENTS The author would like to thank the following individuals for their help in identification of insect specimens: F.H. Rindge of the American Museum of Natural History, R.e. Froeshner and F.e. Thompson of the National Museum of Natural History, e. Mitter and M.A. Solis of the University of Maryland Entomology Department, and especially Rolf Meier. Special appreciation is extended to Rev. and Mrs. e.A. McMullen for their support of this study.

LITERA TURE CITED Beebe, W. (1923)Notes on Galapagos . Zoologica 5: 51-59. Froeshner, R.e. (1985) Synopsis of the Heteroptera or true bugs of the Galapagos Islands. Smithsonian Contributions to Zoology 407: 1-84. Hayes, A.H. (1975) The larger moths of the Galapagos Islands (Geometroidea, Sphingoidea, and ). Proc. Calif. Acad. Sci., ser. 4, 40: 145-208. Linsley, E.G. (1966) Pollinating insects of the Galapagos Islands. In: R.I. Bowman (ed.), the Galapagos pp. 225-232. Univ. Calif. Press, Berkeley and Los Angeles. Linsley, E.G. (1977) Insects of the Galapagos (Supplement). Occas. Papers Calif. Acad. Sci. 125: 1-50. Linsley, E.G. and R.L. Usinger (1966) Insects ofthe Galapagos Islands. Proc. Calif. Acad. Sci., ser. 4, 33: 113-196. Linsley, E.G., Rick, e.M., and S.G. Stephens (1966) Observations on the floral relationships of the Galapagos carpenter bee. The Pan-Pacific Entomologist 42: 1-18. McMullen, e.K. (1985) Observations on insect visitors to flowering plants of Isla Santa Cruz. Part 1.The endemic carpenter bee. Noticias de Galapagos, No. 42. Rick, C.M. (1966) Some - relations on the Galapagos Islands. In: R.I. Bowman (ed.), The Galapagos, pp. 215-224. Univ. Calif. Press, Berkeley and Los Angeles. Rindge, F.H. (1973) The Geometridae (Lepidoptera) of the Galapagos Islands. American Museum Novitates 2510: 1-3\. Wheeler, W.M. (1924) The Formicidae of the Harrison Williams Galapagos Expedition. Zoologica 5: 101- 122. Williams, F.X. (1911) Expedition ofthe California Academy ofSciences to the Galapagos Islands, 1905- 1906. IlI. The butterflies and hawk-moths of the Galapagos Islands. Proc. Calif. Acad. Sci., ser. 4, 1: 289-322.

Table 1. Surnrnary of flower record s for butterflies on Isla Santa Cruz frorn October 1983-March 1984. Planl Visited Insect VL~ltor Localion Activity JUJlicia galapagana (E) [..eploles pa"hasioides Transition Zone, 3.5 km n. moderate (Acanthaceae) (Lycaenidae) Puerto Ayora Tournefortia psi/oslachya (N) [..eploles pa"hasioides Transition Zone, 3.5 km n. modera te (Boraginaceae) (Lycaenidae) Puerto Ayora Mormordica charanlia (CE) [..eploles pa"hasioides Transition Zone, 3.5 km n. low (Cucurhitaceae) (Lycaenidae) Puerto Ayora Vigna IUleola (N) !..eploles pa"hasioides Pampa Zone, 3 km n. low (Fahaceae) (Lycaenidae) Media Luna Cuphea racemosa (1) Leploles pa"hasioides Pampa Zone, 3 km n. high (Lythraceae) (Lycaenidae) Media Luna Gossypium barbadense (E) Phoebis Sennae Arid Zone, low var. dar",inií (Pieridae) Darwin Station (Malvaceae)

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Noticias de Galapagos v.43 1986 Sida rhombifalia (1) Leptates pan ~asiaides Transition Zone, 3.5 km n. high (Malvaceae) (Lycaenidae) Puerto Ayora COl/1l11icmpl/Jtl/berosl/s (N) Leptotes parrhasioides Arid Zone, low (Nyctaginaceae) (Lycaenidae) Darwin Station I'lumbaga scandens (N) l'haebis sennae Transition Zone, 3.5 km n. low (Plumbaginaceae) (Pieridae) Puerto Ayora Leptates parrhasiaides Transition Zone, 3.5 km n. low (Lycaenidae) Puerto Ayora Tribulus cistaides (1) Leptotes parrhasiaides Arid Zone. low (Zygophyllaceae) (Lycaenidae) Darwin Station

Table 2. Summary of flower records for moths on Isla Santa Cruz fram October 1983-March 1984. Plant Visited Insect Visitor Localion Activity CO/'dia leucophlyctis (E) DiscliJiaprocta stellata Arid Zone, high (Boraginaceae) (Geometridae) Darwin Station 1 Taurn~rartia psilastachya (N) Unidentified Arid Zone, low (Boraginaceae) (Pyralidae) Darwin Station Carica papaya (CE) Agrius cingulatus Arid Zone. high (Caricaceae) (Sphingida'e) Darwin Station Clemdcndrum malle (N) Unidentified genus Arid Zone. moderate var. malle (Sphingidae) Darwin Station (Verbenaceae)

Table 3. Summary of flower records for ants on Isla Santa Cruz fram October 1983-March 1984. Plants Visited Insect Visitor Location Activity Justicia galapagana (E) Wamrannia aurapunctata Transition Zone, 3.5 km n. low (Acanthaceae) (Formicidae) Puerto Ayora A,'icennia gCl11linans(N) Paratrechilla langicarnis Littoral Zane. I)igh (Avicenniaceae) (Formicidae) Tortuga Bay Tapillama mclanacephalum Littoral Zane. high (Formicidae) Tortuga Hay CO/'dia lutea (N) Wamrannia aurapunctata Arid Zone. moderate (Horaginaceae) (Formicidae) Darwin Station Paratrechilla vaga Arid Zone. low (Formicidae) Darwin Station Mormordica charantia (CE) Wasmanllia aurapunctata Transition Zone. 3.5 km n. moderate (Cucurbitaceae) (Formicidae) Puerto Ayora l'msnpis julifTora (N) Tapinoma melanacephalum Littoral Zone. low (Fabaceae) (Formicidae) Tortuga Hay Setaria geniculata (N) Wamranllia auropunctata Arid Zone. high (Poaceae) (Formicidae) Darwin Station Capsicum frutescens (CE) Wasmannia auropunctata Transition Zane. 3.5km n. high (Solanaceae) (Formicidae) Puerto Ayora Clerodcndrum molle (N) Unidentified genus Arid Zone. low var. molle (Formicidae) Darwin Station (Verbenaceae)

Table 4. Summary of flower record s for hover flies and stilt bugs on Isla Santa Cruz from October 1983-March 1984 Plant Visited Insect Visitar Locafion Activity Ageratum canazoides (1) Toxomerus crockeri Pampa Zane, 3 km n. high (Asteraceae) (Syrphidae) Media Luna Jaegeria gracilis (E) Toxomerus crockeri Pampa Zone, 3 km n. high (Asteraceae) (Syrphidae) Media Luna Olphea racemasa (1) Toxomerus crockeri Pampa Zane. 3 km n. high (Lythraceae) (Syrphidae) Media Luna Polygonum opelousanum Toxomerus crockeri Pampa Zane. 3 km n. low (Polygonaceae) (Syrphidae) Media Luna Diodiá radula (1) Toxamerus crockeri Pampa Zane, 3 km n. low (Rubiaceae) (Syrphidae) Media Luna Cordia lutea (N) Metacanthus galapagensis Arid Zane. high (Boraginaceae) (Berytidae) Darwin Station

(E) endemic (N) native (1) introduced weed (CE) cultivated escape

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Noticias de Galapagos v.43 1986